Difference between revisions of "Talk:O2k-chamber"
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'''Calibration and quality control of the OroboPOS (O2k-SOP)''' in [[MiPNet06.03 POS-Calibration-SOP]]. | '''Calibration and quality control of the OroboPOS (O2k-SOP)''' in [[MiPNet06.03 POS-Calibration-SOP]]. | ||
Possible instrumental and protocol related causes for fluxes differing between chambers | Possible instrumental and protocol related causes for fluxes differing between chambers: | ||
* wrong O2 calibration in one chamber | * wrong O2 calibration in one chamber, see [[MiPNet06.03 POS-Calibration-SOP]] | ||
* wrong chamber volume calibration: The total amount of oxygen in the chamber with the smaller volume will be smaller. Therefore the O2 concentration will drop faster resulting in a higher flux. | * wrong chamber volume calibration: The total amount of oxygen in the chamber with the smaller volume will be smaller. Therefore, the O2 concentration will drop faster resulting in a higher flux, see [[MiPNet19.18A O2k-Start]]. | ||
* wrong background parameters: wrong background parameters will cause a O2 concentration dependent offset to the flux, the value of the offset will be independent of the absolute value of the flux. E.g. a constant offset of 10 pmol /ml s at ca 100 µM O2 concentration and 20 pmol/ml s at 300 µM O2 concentration could be caused by wrong background parameters, but a difference of always 20% at very different absolute values of the flux can not be caused by wrong background parameters. In any case it is advisable to check the background parameters ( redo an instrumental O2 background experiment). | * wrong background parameters: wrong background parameters will cause a O2 concentration dependent offset to the flux, the value of the offset will be independent of the absolute value of the flux. E.g. a constant offset of 10 pmol /ml s at ca 100 µM O2 concentration and 20 pmol/ml s at 300 µM O2 concentration could be caused by wrong background parameters, but a difference of always e.g. 20% at very different absolute values of the flux can not be caused by wrong background parameters. In any case it is advisable to check the background parameters ( redo an instrumental O2 background experiment). See [[MiPNet14.06 InstrumentalBackground]]. | ||
* hydrophobic inhibitors | * hydrophobic inhibitors, see [[MiPNet19.03 O2k-cleaning and ISS]] | ||
* biological contamination | * biological contamination, see [[Biological contamination]] | ||
Hardware defects: While hardware defects (sensors, electronics,..) can obviously have many negative effects (noise signal, slow response, no signal,..) it is difficult to see how a real hardware defect can cause a systematic error in flux calculation once it was possible to do a correct calibration of the O2 sensor (at air saturation and at zero oxygen). | Hardware defects: While hardware defects (sensors, electronics,..) can obviously have many negative effects (noise signal, slow response, no signal,..) it is difficult to see how a real hardware defect can cause a systematic error in flux calculation once it was possible to do a correct calibration of the O2 sensor (at air saturation and at zero oxygen). | ||
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Different fluxes in left and right chmaber
Question: In our experiments we get consistently higher fluxes in chamber A as compared to chamber B.
Answer: To exclude instrumental causes please follow the procedure described in the section Calibration and quality control of the OroboPOS (O2k-SOP) in MiPNet06.03 POS-Calibration-SOP.
Possible instrumental and protocol related causes for fluxes differing between chambers:
- wrong O2 calibration in one chamber, see MiPNet06.03 POS-Calibration-SOP
- wrong chamber volume calibration: The total amount of oxygen in the chamber with the smaller volume will be smaller. Therefore, the O2 concentration will drop faster resulting in a higher flux, see MiPNet19.18A O2k-Start.
- wrong background parameters: wrong background parameters will cause a O2 concentration dependent offset to the flux, the value of the offset will be independent of the absolute value of the flux. E.g. a constant offset of 10 pmol /ml s at ca 100 µM O2 concentration and 20 pmol/ml s at 300 µM O2 concentration could be caused by wrong background parameters, but a difference of always e.g. 20% at very different absolute values of the flux can not be caused by wrong background parameters. In any case it is advisable to check the background parameters ( redo an instrumental O2 background experiment). See MiPNet14.06 InstrumentalBackground.
- hydrophobic inhibitors, see MiPNet19.03 O2k-cleaning and ISS
- biological contamination, see Biological contamination
Hardware defects: While hardware defects (sensors, electronics,..) can obviously have many negative effects (noise signal, slow response, no signal,..) it is difficult to see how a real hardware defect can cause a systematic error in flux calculation once it was possible to do a correct calibration of the O2 sensor (at air saturation and at zero oxygen).
